A multifunction peripheral is a device that performs a variety of functions of a scanner, a copier and a printer. Nowadays, multifunction peripherals become essential electronic devices for most enterprises or individual users. FIG. 1 schematically illustrates a process of performing a printing operation in a multifunction peripheral according to the prior art. Conventionally, for printing a document (e.g. a photo) by the multifunction peripheral, the photo 1 is firstly placed on a scanning window 2. Then, a scanning module within the multifunction peripheral is moved in a scanning direction Y to scan the photo 1. The scanned image data are successively stored into the dynamic memory within the multifunction peripheral on a line image basis. The line image 3 comprises plural pixels 4, which are arranged in a line. After several line images 3 stored in the dynamic memory are accumulated as a band image 5, the multifunction peripheral performs an image processing operation on the basis of a single band image 5. Then, plural processed band images 5 are combined as an original image 6, which is transmitted to the multifunction peripheral on a band image basis to be printed out.
Moreover, in a case that the document to be printed has a small image portion, the user may hope only the image portion is scanned because it is time-saving for the multifunction peripheral to scan only the image portion. As shown in FIG. 1, the original image 6 comprises an object image 7 and the rest of the object image 7 (i.e. a blank image). For acquiring only the object image 7, the multifunction peripheral usually provides an image cropping process. That is, before the scanning operation is done, a pre-scanning operation is performed to quickly scan the document at a low resolution. By performing the pre-scanning operation, the object image size of the original image and the desired scanning position can be recognized. After the actual range of the object image to be scanned is reset, the regular scanning operation will be done.
The pre-scanning operation used in the image cropping process, however, still has some drawbacks. For example, even if the area of the object image to be scanned is very small, the time for performing the pre-scanning operation is needed. For example, if a multifunction peripheral having an A3-sized scanning window is used to scan a 3×5 photo, the conventional image cropping process needs to firstly scan the A3-sized scanning window. After the position of the photo is recognized by an algorithm, the scanning range is reset and then the scanning operation is performed. Moreover, since the dynamic memory of the ordinary multifunction peripheral has a limited capacity, the original data produced by the pre-scanning operation need to be stored in the dynamic memory of the multifunction peripheral. The image data comprise the scanning data of the image zone and the data of the blank zone. Since the image data occupy a large portion of the dynamic memory, the image processing speed of the multifunction peripheral is impaired.
From the above discussions, the conventional image cropping process is time-consuming. Regardless of the object image size, a pre-scanning cycle is required and a large portion of the dynamic memory is occupied.